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Roughing cut without bevel support

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Forum topic by JoshNZ posted 07-13-2017 06:08 AM 758 views 0 times favorited 13 replies Add to Favorites Watch
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JoshNZ

85 posts in 908 days


07-13-2017 06:08 AM

Topic tags/keywords: bowl

https://youtu.be/LTGeWtFrKN4?t=50s

What is this cut called 50 seconds into this video? I see it a lot when guys are roughing green wood particularly when they’re knocking the corner off the bowl for the curve to the foot. To me it looks like there is never any bevel support. Or if there is it’s on the wing and it looks like a huge amount of material is being taken off.

How is this done and how is a catch avoided? Can it only be done on green wood?


13 replies so far

View Wildwood's profile

Wildwood

2187 posts in 1973 days


#1 posted 07-13-2017 12:20 PM

He is using both scraping and bevel riding cuts. Other than when grabs a scraper at the end of the video all of his pull cuts use sides of the flutes (wings) to scrap, on his push cuts he is riding the bevel.

-- Bill

View TheDane's profile

TheDane

5333 posts in 3502 days


#2 posted 07-13-2017 01:13 PM

What is this cut called 50 seconds into this video?

Looks like a shearing cut. You do this with minimal over hang and let the tool rest absorb the downward force.

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

View Bill White's profile

Bill White

4807 posts in 3799 days


#3 posted 07-13-2017 01:39 PM

And remember that he is not doing finishing cuts.
Bill

-- bill@magraphics.us

View Wildwood's profile

Wildwood

2187 posts in 1973 days


#4 posted 07-13-2017 01:43 PM

Left out shear scraping cause he is using combination of straight pull cuts and dropping the tool handle shear scraping to hog off wood. Came up learning the push cut for everything and some where along the way picked up push cuts.

-- Bill

View SignWave's profile

SignWave

440 posts in 2874 days


#5 posted 07-13-2017 02:05 PM

I share your interest in this kind of cut. I have also wondered how people are able to do this without it catching. It’s something you see with Ellsworth grinds particularly, which I think is a subtle but necessary factor in why this doesn’t catch.

I think if you asked this turner what he was doing, he’d probably call it a pull cut, and it does have bevel support. Look at the side of the gouge nearest to the camera and you can see that on the sides, the bevel is sloped inward toward the flute. That not only allows but really requires that the flute be pointed toward the workpiece in order for the edge to contact the wood. This is why I think it’s bevel supported.

If we were watching an overhead shot, I think we’d also see that the point of contact is very close to the centerline of the tool. This goes a long way toward keeping the tool from rotating toward the work, and is again related to the way the bevel is ground.

It still looks precarious to me because the cutting edge is nearly perpendicular to the rotation, and watching it, I want to pull the handle down to get more of an angle. I currently use more of a Stuart Batty 40/40 grind on my bowl gouge. The difference in grind definitely affects the technique.

my .02, fwiw

-- Barry, http://BarrysWorkshop.com/

View OSU55's profile

OSU55

1426 posts in 1828 days


#6 posted 07-13-2017 02:26 PM

Its just a scraping cut using the lower wing of an Ellsworth or other long wing grind. Very safe cut, use it often. Good for roughing, especially wet wood. For finish cuts, drop the handle such that the cutting edge is at least 45* to the spindle axis/ surface, called sheer scraping.

Using both the scraping cut along with bevel push cuts when roughing just uses more of the sharpened edge of the tool, providing more cutting time between sharpenings.

View LeeMills's profile

LeeMills

461 posts in 1140 days


#7 posted 07-13-2017 02:42 PM

Only from my perspective…
Riding/rubbing the bevel is from solid or imaginary wood. Consider roughing a square while spindle turning, to start you are only rubbing the bevel on 90% air. This is why stance vs arm movement is very important. The same applies to bowl turning. You turn with your body, not your arms (if your other life is a brain surgeon the you may have steady enough hands to not use your body).

There are four basic cuts, the push cut and pull cut where it depends on if the bevel is leading or following the cut and the scrape or sheer where the flute is almost completely closed but the position of the handle changes.
This video by Lyle Jamieson shows starting a rough turning. Don’t try the two finger cut yet.
He starts with the same imaginary support but it is easy because he is using proper stance and moving with his body, not pushing the tool into the wood so it is very controlled.

https://www.youtube.com/watch?v=X06EjQhDROk

-- We cannot solve our problems with the same thinking we used when we created them. Albert Einstein

View SignWave's profile

SignWave

440 posts in 2874 days


#8 posted 07-13-2017 03:48 PM

I went back and watched that section again, slowed down to .25x speed. If you watch the shadow line of the wood, it appears that the part of the gouge that is actually doing the cutting is a lot closer to the tip than it might seem. It’s definitely on the side, and it’s more aggressive than I’d like to cut, but still close to the tip.

Back to the OP. I think asking this kind of question is an excellent way of improving your skills. You will find different turners with very different approaches, and sometimes it seems like one approach is violating a “rule” put forward by another turner. But the wood will let you know when you’ve done something wrong, by giving a catch, tearout, or a rough surface. Theory goes out the window when the bowl flies across the room (or into your head).

-- Barry, http://BarrysWorkshop.com/

View JoshNZ's profile

JoshNZ

85 posts in 908 days


#9 posted 07-13-2017 10:47 PM

https://youtu.be/xBNAkRe9bxw?t=3m10s

This is probably a better demonstration + explanation of something similar (I think!) by Brendon Stamp at 3:10. It looks like a very useful cut they seem to be able to shred wood off at a hell of a rate, which is what you want when you’re roughing green wood that is going to need to be re turned anyway.

I’m not calling anyone wrong but I’d be surprised if it were just a scraping cut, I’ve never been able to scrape/sheer scrape that deep. At 1.10 that cut looks almost 3/8” deep!
https://youtu.be/LTGeWtFrKN4?t=1m10s

I’ve spent many hours watching Lyle Jaimesons videos I really like them. And I do rough green stuff pretty much the way he does there but it isn’t quite what we are seeing in the other videos, I don’t think.

View Karda's profile

Karda

823 posts in 393 days


#10 posted 07-14-2017 12:38 AM

any idea what angle his gouge is ground at. I grind mine at 65 degrees and in order to cut down the side of the bowl like he does I have to stand at the end of the lathe and the gouge is very close to 90 degrees to the lathe rails, very awkward. what am I doing wrong

View TheDane's profile

TheDane

5333 posts in 3502 days


#11 posted 07-14-2017 01:24 AM

Those who referenced David Ellsworth’s techniques are spot-on. David actually teaches what he calls the “shear cut” in his bowl-turning workshops. With his signature gouge (ground to 60-degrees) he shears off long streamers of shavings.

Ellsworth teaches 3 cuts for the outside of a bowl … the “rough cut” knocks off the corners, resulting in a rough shape. He refines the shape with the “shear cut”, then finishes the outside of the piece with “shear scraping”.

From what I can see in the video, this is not a scrape, but is a shear cut.

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

View OSU55's profile

OSU55

1426 posts in 1828 days


#12 posted 07-14-2017 03:20 PM

In case one hasnt realized, 2 different cuts are being confused. One is what I call a scraping cut, where the tool handle is approx parallel with the ground. This is a roughing, shaping cut – it will tear out. The other is a sheer scrape, where the handle is dropped to ~ 45. This is a light finish type cut which clear up the tron grain by the scrape cut or furrows left by a bevel cut.

The tool bevel angle isnt the key element, as Ive used 40-65 bevel angles for both cuts. The key is having long wings ground on the gouge, hence the mention of “Ellsworth”. Either cut is a bit dangerous with short wings.

(Not sure why some of this is bold)

View JoshNZ's profile

JoshNZ

85 posts in 908 days


#13 posted 07-15-2017 09:27 PM

Whatever it is I had a go at it today and it is awesome. I certainly wasn’t scraping in any sense of the word. I have been turning a stubborn piece of sweet chestnut (which I’ve found to be a disappointment) and dulling tools, getting burnt on sawdust etc… This technique made it like going back to green wood. Huge thick shavings pouring off it with a wooshing noise. I’m surprised. Much more efficient than push cutting with the tip.

Good one to have under the belt anyway I’ll give it some more practice.

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